Kiln



0. M. WICKEN ETL KILN Filed May 2, 1963 Feb. 9, 1965 KILPJ @saar M. Wieken and Richard R. Schneider, Pittsburgh, Pa., assignors to Harbisdn-Walker Refractories Corn" pany, fittsnnrgh, Pa., a corporation of Pennsylvania Filed May 2, i953, Ser. No. 277,567 2 Claims. (Cl. 26332) This invention relates to high temperature processing apparatus and more particularly, it concerns an improved lifter construction for use in rotary kilns, calciners, dryers, and other rotary processing funaces or vessels.

Rotary kilns are well known in the art and are generally comprised of an elongated, refractory lined cylinder adapted to be rotatably supported with its axis inclined so that various types of granular, particulate or more generally fluent materials may be made to ilow from the upper to the lower end of the cylinder to be heated by counter or concurrently flowing hot combustion gases. ln order to agitate the fluent material and thus expose it more completely to the atmospheric of combustion gases in the kiln, heretofore, lifters consisting of small ledges extending from the refractory lining of the kiln toward the center thereof have been used. The lifters function to carry the load of fluent material upwardly on the rising side of the rotating cylinder and to spill or drop the material downwardly into intimate contact with the combustion gases. They are generally made either from metal for low temperature application or from certain spallresistant refractories for high temperature work. Among the major problems incurred by the use of lifters of this type in the past :has been extremely limited capacity, particularly where the lifter has been formed from refractory material. Principally because of the weak structural characteristics of the refractory material, the lifters can extend only a small distance from the inner wall of the kiln and therefore only a small amount of material can be elevated and dr-opped through the combustion gas stream. Furthermore, even the most soundly designed refractory lifters heretofore available have been very sensitive to thermal spalling and subject to mechanical breakage.

In accordance with the present invention, the problems previously incurred with rotary kiln lifters are substantially diminished by providing lifters in the form of apertured radial baffles extending longitudinally of the rotary kiln shell and converging centrally thereof to provide interdependent support of the baffles. In this manner, the desirable heat exchange characteristics of structurally weak refractory material may be employed while optimum lifting capacities are obtained with diminished danger of thermal spalling and mechanical breakage.

Accordingly, a principal object of the present invention is the provision in a rotary apparatus for processing fluent material at high temperature of an improved lifter construction by which the problems heretofore encountered are effectively and substantially overcome.

Another object of this invention is to provide a rotary kiln lifter construction capable of greater lifter capacity for material resulting in more positive displacement through the center of the kiln gas stream and better distribution of the material through the gas stream than lifter constructions heretofore available.

A further object of this invention is to provide an improved lifter construction of the type referred to having inherent structural stability thereby enabling the benefit of contact between the kiln load and much hotter refractory material than was practical with lifters available prior to this invention.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter in conjunction with the at- Sates Paten .Mhle

tached drawings wherein like reference numerals designate like parts and in which:

FlG. 1 is a side view of a rotary kiln partially broken away to show the lifter construction of the present invention in central longitudinal section;

FlG. 2 is an enlarged cross-section taken along line 2 2 of FIG. 1 and showing a preferred form of the present invention; and

FlG. 3 is a section taken along line 3 3 of FIG. 2.

Referring now to the drawings and particularly to FlG. 1, a rotary kiln is shown conventionally including an elongated cylindrical metal shell l@ having a lining of refractory bricks l2. The axis of the shell tlis inclined to horizontal so that a load of granular, particulate or gen- .erally fluent material may be introduced at its elevated end to flow downwardly through the kiln as it rotates for discharge from its lower end. As is well known to those skilled inV this art, the kiln may be supported on tires Al and rotatably driven by conventional means not shown. Also, in accordance with one conventional practice, hot combustion gases are delivered to the lower end of the kiln to flow upwardly in counter current relation to the fluent material load moving downwardly through the kiln.

In accordance with the present invention, a plurality of lifters 16 in the form of radial walls or baffles each having a plurality of apertures It formed therein extend longitudinally of at least an intermediate portion of the shell lll. In the embodiment illustrated in FIGS. 2 and 3 of the drawing, three baflles 16 are provided and shaped in cross-section to define three ovate tunnels 2li. The tunnels 2li do not extend the entire length of the kiln. Each of the baffles 16 includes an outer section 22, an intermediate or central section .24 and an inner section 26. in the form shown, the outer section 22 of each baffle is built up of refractory bricks and mortar to define a fillet shape merging with the refractory lining l2 of the kiln. The inner sections 26 are similarly formed and fillet shaped to converge with the central sections respectively of the other baffles to provide interdependent support of the baliles at the central axis of the kiln. The intermediate or central section 24, in the embodiment of FIGS. 2 and 3, is constructed as a wall of rectangular refractory brick 2S arranged in staggered tiers 2% and having conventional complementing tongues and grooves to afford some degree of mechanical interlock. As best shown in FIG. 3, at least the bricks 28 in alternate tiers are dimensioned to 'be spaced in the longitudinal direction of the kiln to define the apertures 1S. Thus, by employing brick of different dimensions in alternate tiers, the brick may be aligned with complementary tongues and grooves to provide natural apertures, thereby eliminating the possibility of disturbing the structural integrity of the brick as where the apertures are provided by some mechanical means, such as drilling. Although it is preferred to have only the bricks in alternate tiers arranged with their ends spaced to provide the apertures 18 for purposes of assuring adequate structural strength for the lifter, it will be apparent that other arangements similar to that illustrated in FIGS. 2 and 3 could be employed without departing from the inventive concept thereof. For example by using appropriately shaped refractory bricks the apertures could be formed by spacing the bricks 28 in each tier Z9.

In use, the fluent material load will be picked up by the lifters or bailies 16 on the rising side of the rotating kiln and dropped through the apertures 18 into intimate contact with the counter flowing hot combustion gases for effective heat processing. Because of the symmetrical disposition of the bal-lies about the cylindrical kiln and the manner in which they are afforded interdependent central support, maximum structural support is afforded to the bullies formed of otherwise weak refractory material.

3 Also, the shelf capacity and thus the lifting capacity of the bafties 16 approaches an optimum amount because of their extent throughout the complete radius of the kiln.

The embodiment of FIGS. 2 and 3 is intended for use with kilns having extremely large diameters, such as, for example, l0 ft. in diameter and larger. In smaller kilns, it is economically practical for the baffles 16 to extend substantially the entire length of the kiln.

Thus, it will be seen from the description given, the above-mentioned objectives are completely fulfilled. The extension of the lifters or baffles 16 from the outer periphery shell across its radial extent to converge at the center affords maximum lifting capacity together with structural stability thereby enabling the use of high temperature cha'racteristics of refractory material throughout. Moreover, because of the amount of refractory material presented within the kiln coming in contact with the load, considerably improved heat distribution is afforded.

In some aspects, this invention relates to improvements in kilns of the type disclosed in U.S. Patent 3,030,091, owned by the same assignee as the instant invention.

From the above description and the attached drawings it will be apparent to those skilled in this art that numerous modifications of the preferred embodiments described and illustrated herein are possible. Accordingly, it is to be distinctly understood that the foregoing description is illustrative only, not limiting, and that the true spirit and scope of the present invention is to be determined by reference to the appended claims.

The invention claimed is:

l. In a rotary kiln of the type including an inclined cylindrical shell having a refractory material lining and adapted to pass a load of fluent material into contact with a stream of hot combustion gases, means for lifting the fluent material and dropping it through the hot combustion gases comprising a plurality of refractory baies extending at least an intermediate longitudinal portion of the shell, said baffles having an outer fillet-shaped section merging with the refractory lining in the cylindrical shell, an inner fillet-shaped section and an intermediate section extending between said inner and outer sections coverging centrally thereof to provide independent support for said bai'lies, said intermediate section being formed of v staggered tiers of refractory brick consisting at least in part of complementary tongue and groove brick in the longitudinal direction of the kiln, said brick being so dimensioned in alternate tiers, that when the complementary tongues and grooves are aligned, natural apertures are provided along the length of each baffle to permit the lluent load material to be picked up by said baffles during rising thereof due to rotation of the shell and dropped through the apertures into contact with the counterflowing combustion gases.

2. In a rotary kiln of the type including an inclined cylindrical shell having a refractory material lining and adapted to pass a load of uent material into contact with a stream of hot combustion gases, a portion of the kiln being provided with three uniformly spaced radial partition walls meeting at the center of the kiln and extending lengthwise of it, said walls being made of refractory material only and shaped to form with said lining a cluster of three tunnels, ovate in cross-section, and the opposite sides of the outer portion of each partition wall being concave, each of said radial partition walls being formed of staggered tiers of refractory brick consisting at least in part of complementary tongue and groove brick in the longitudinal direction of the kiln, said brick being so dimensioned in alternate tiers, that when the complementary tongues and grooves are aligned, natural apertures are provided along the length of each baffle to permit the fluent load material to be picked up by said baffles during rising thereof due to rotation of the shell and dropped through the apertures into contact with the counterowing combustion gases.

References Cited by the Examiner UNITED STATES PATENTS 1,779,626 10/30 Horn et al 263-33 3,030,091 4/62 Wieken et al 263-32 FOREIGN PATENTS 948,774 2/49 France.

CHARLES SUKALO, Primary Examiner.

JOHN J. CAMBY, Examiner. 

1. IN A ROTARY KILN OF THE TYPE INCLUDING AN INCLINED CYLINDRICAL SHELL HAVING A REFRACTORY MATERIAL LINING AND ADAPTED TO PASS A LOAD OF FLUENT MATERIAL INTO CONTACT WITH A STREAM OF HOT COMBUSTION GASES, MEANS FOR LIFTING THE FLUENT MATERIAL AND DROPPING IT THROUGH THE HOT COMBUSTION GASES COMPRISING A PLURALTIY OF REFRACTORY BAFFLES EXTENDING AT LEAST AN INTERMEDIATE LONGITUDINAL PORTION OF THE SHELL, SAID BAFFLES HAVING AN OUTER FILLET-SHAPED SECTION MERGING WITH THE REFRACTORY LINING IN THE CYLINDRICAL SHELL, AN INNER FILLET-SHAPED SECTION AND AN INTERMEDIATE SECTION EXTENDING BETWEEN SAID INNER AND OUTER SECTIONS COVERGING CENTRALLY THEREOF TO PROVIDE INDEPENDENT SUPPORT FOR SAID BAFFLES, SAID INTERMEDIATE SECTION BEING FORMED OF STAGGERED TIERS OF REFRACTORY BRICK CONSISTING AT LEAST IN PART OF COMPLEMENTARY TONGUE AND GROOVE BRICK IN THE 